Definition for Coal
From Biology Forums Dictionary
1. Coal is a brown or black carbonaceous deposit derived from the accumulation and alteration of ancient vegetation, which originated largely in swamps or other moist environments. As the vegetation decomposed it formed layers of peat, which were subsequently buried. Under the increased pressure and the resulting higher temperatures the peat was transformed into coal.
2. Organic matter (woody plant material) that was compressed under very high pressure to form dense, solid carbon structures.